Mr Gray, an honorary senior lecturer at the University of Manchester, said amphibians, including toads, frogs and newts were “very susceptible” to pesticides, which get into their environment and this can cause the deformity.
He added some amphibians could also regenerate limbs if they sustained damage when they were young, or even in the tadpole stage of life.
“The leg bud looks like it has been damaged, so what I think has happened here is its body has thought it’s lost a leg, so it’s generated a new one from the actual limb bud,” Mr Gray said after seeing a photograph of the toad.
“Looking at the other leg, it looks like its damaged to a degree and lost a few of its digits.”